1. Field of the Invention
The present invention relates generally to a Network Sharing (NS) system. In particular, the present invention relates to a method of signaling network sharing information about neighbor cells to User Equipments (UEs), a UE operation in relation to the signaling, and an NS system therefor.
2. Description of the Related Art
A mobile communication system basically includes Radio Access Networks (RANs) and UEs. Each RAN, basically having a Node B, is connected to another network through a Core Network (CN). In doing so, RANs using different Radio Access Technologies (RATs) or operated by different operators, can access one or more CNs operated by the same or different CN operators. A technology of sharing a RAN among different CN operators is called network sharing (NS).
In a Code Division Multiple Access (CDMA) cellular mobile communication system compliant with the 3rd Generation Partnership Project 2 (3GPP2) standards, a RAN includes a Base Transceiver Subsystem (BTS) and a Base Station Controller (BSC). The RAN is connected to a CN with a Mobile Switching Center (MSC). In Wideband CDMA (WCDMA) based on Global System for Mobile telecommunications (GSM) and General Packet Radio Service (GPRS) in compliance with the 3GPP standards, namely Universal Mobile Telecommunication System (UMTS), a RAN includes a cell and Node B, and a Radio Network Controller (RNC). The RAN is connected to a CN with a Serving GPRS Support Node (SGSN).
The CN operators are identified by their Public Land Mobile Network (PLMN) Identities (ids). Each PLMN id is made of a Mobile Country Code (MCC) and a Mobile Network Code (MNC). A UE selects the PLMN id of an intended CN operator autonomously or under the control of a network. To access the CN, the UE notifies its serving RAN of the selected PLMN id.
To move to a neighbor cell belonging to a more suitable CN operator, it needs to receive network sharing information indicating CN operators associated with neighbor cells.
Accordingly, a need exists for a system and method for efficiently signaling the network and sharing information of neighbor cells to a UE so that the UE can select the best CN operator during inter-cell roaming.